To complete a well, various completion equipment is provided in a well. In many cases, the completion equipment includes electrical devices that have to communicate with an earth surface or downhole controller. Traditionally, electrical cables are run to downhole locations to enable such electrical communication. In other implementations, inductive couplers have been used for communicating power and/or signaling to electrical devices downhole in a wellbore and retrieving measurement information to surface.
Typically, an inductive coupler includes two coil elements, a female coil element that is fixed in a downhole position, and a male coil element that is typically run with a tool for positioning adjacent the female coil element to enable inductive coupling between the female and male coil elements. In downhole applications, both the male and female coil elements of an inductive coupler are typically arranged in cylindrical structures. Each of the male and female coil elements includes a pole member (formed of a ferromagnetic material) that is cylindrically shaped. Each coil element has coil wiring that is wound along a circumference of the respective cylindrical pole member.
A side sectional view of an example conventional inductive coupler 10 is depicted in FIG. 1, which shows a cylindrically-shaped female pole member 12 and a cylindrically-shaped male pole member 14. Coil wiring 16 is provided in a circumferential groove 18 defined in the female pole member 12, and coil wiring 20 is provided in a circumferential groove 22 defined in the male pole member 14. Note that the cylindrically-shaped male pole member 14 has an outer diameter that is smaller than an inner diameter of the female pole member 12, such that the male pole member 14 can be lowered into the inner bore of the female pole member 12 to enable inductive coupling between the male and female coil elements. Once the female and male coil elements are aligned, an electrical current is run through one of the coil wirings 16, 20, which creates a magnetic field 24 to induce current to flow in the other of the coil wirings 16, 20.
An issue associated with using a conventional inductive coupler such as that depicted in FIG. 1 is that it may be difficult or not cost-effective to make inductive couplers of different sizes for different applications. Cylindrically-shaped pole members made of certain types of ferromagnetic materials can be mechanically fragile, making the grinding process relatively difficult to achieve coupler elements of different sizes as well as making the inductive coupler easily susceptible to failure due to mechanical shocks or vibrations during deployment downhole or operation within the wellbore. Also, having to provide customized sizes and shapes to achieve coupler elements of different sizes is a time-consuming and labor-intensive process, which can drive up the costs of well operation. Also, an issue associated with conventional inductive couplers is that the ferromagnetic core and the coil element are exposed to well bore fluids which result in corrosion and reduced life span.